Fatty Acid Synthase, Caveolin-1 and Membrane Microdomains in Prostate Cancer

描述（由申请方提供）：脂肪酸合成酶（FAS）（一种主要的脂肪生成酶）和小窝蛋白-1（Cav-1）（一种转运胆固醇并调节信号转导的膜蛋白）均在前列腺癌（PCa）的人类和动物模型中过表达。这两种蛋白质在PCa细胞中发挥致癌功能。现在，我们第一次获得了初步结果，表明FAS和Cav-1在PCa细胞中相互作用，FAS是一种胞质蛋白，可以被诱导与富含胆固醇的脂筏膜相关联。进一步的数据表明，在棕榈酰化缺陷的Cav-1突变体中，两种蛋白质之间的复合物形成受损。我们也有证据表明，Cav-1棕榈酰化可能在信号转导中发挥作用，EGFR激活的侵袭性PCa细胞的结果，在快速形成的膜囊泡，含有脂筏组件以及膜Cav-1。由于Cav-1是侵袭性前列腺癌的循环标志物，因此这些分泌的囊泡可能与转移性播散有关。最后，我们已经获得的证据表明，Cav-1和FAS栖息在人类肿瘤中相似的亚细胞位置，允许两种蛋白质在体内的合作。 在本项目概述的实验中，我们将挑战以下总体假设：Cav-1和FAS合作改变脂筏隔室，有助于形成富含胆固醇和饱和脂肪酸的膜环境。细胞膜的这些变化可能对肿瘤细胞的存活、生长和其他恶性行为产生重要的功能性影响。Cav-1和FAS共定位也可能是一个有用的预后指标。本研究的具体目的是：目的1：确定脂肪酸合酶和小窝蛋白-1是否合作改变PCa细胞的膜组成和膜动力学。我们将测试以下假设：（i）c-Src的激活决定FAS在膜上的定位，并且FAS和Cav-1共定位在质膜和/或其他细胞膜上，（ii）FAS和Cav-1改变膜组成和动力学，（iii）FAS在蛋白质棕榈酰化中起作用。目的2：探讨脂肪酸合成酶和小窝蛋白-1在前列腺癌细胞膜共定位的生物学意义。我们将检验以下假设：（i）FAS在细胞膜上的定位是致癌的。(ii)FAS和Cav-1共定位分层人类肿瘤的生物学行为。（iii）FAS和Cav-1合作，以介导的分泌Cav-1-含有囊泡。我们相信，这些实验将提供新的见解Cav-1和FAS在PCa中的作用，并将扩大我们的理解的性质，程度和相关的PCa和其他可能的恶性肿瘤的肿瘤发生的膜脂质变化的生物学意义。

DESCRIPTION (provided by applicant): Fatty Acid Synthase (FAS), a major lipogenic enzyme, and Caveolin-1 (Cav-1), a membrane protein that transports cholesterol and regulates signal transduction, are both over-expressed in human and animal models of prostate cancer (PCa). Both proteins exert an oncogenic function in PCa cells. Now, for the first time, we have acquired preliminary results demonstrating that FAS and Cav-1 interact in PCa cells and that FAS, a cytosolic protein, can be induced to associate with cholesterol-rich, lipid raft membranes. Further data show that complex formation between the two proteins is impaired in a Cav-1 mutant deficient in palmitoylation. We also have evidence suggesting that Cav-1 palmitoylation may play a role in signal transduction and that EGFR activation of aggressive PCa cells results in rapid formation of membrane vesicles that contain lipid raft components as well as membrane Cav-1. Because Cav-1 is a circulating marker for aggressive PCa, these secreted vesicles may be linked to metastatic dissemination. Finally, we have acquired evidence indicating that Cav-1 and FAS inhabit similar subcellular locations in human tumors, allowing for cooperation between the two proteins in vivo. In the experiments outlined in this project, we will challenge the following overall hypothesis: Cav-1 and FAS collaborate to alter the lipid raft compartment, contributing to a membrane environment that is richer in cholesterol and saturated fatty acids. These changes in cell membranes may exert important functional consequences on tumor cell survival, growth and other malignant behaviors. Cav-1 and FAS colocalization might also be a useful prognostic indicator. The specific aims of the study are: Aim 1: Determine whether Fatty Acid Synthase and Caveolin-1 collaborate to alter membrane composition and membrane dynamics in PCa cells. We will test the hypotheses that: (i) Activation of c-Src determines FAS localization at the membrane, and FAS and Cav-1 co-localize at the plasma membrane and/or at other cellular membranes, (ii) FAS and Cav-1 alter membrane composition and dynamics, (iii) FAS plays a role in protein palmitoylation. Aim 2: Determine the biological significance of Fatty Acid Synthase and Caveolin-1 colocalization at cell membranes in PCa. We will test the hypotheses that: (i) FAS localization at the membrane is oncogenic. (ii) FAS and Cav-1 co-localization stratifies human tumors with respect to biological behavior, (iii) FAS and Cav-1 collaborate to mediate the secretion of Cav-1-containing vesicles. We believe these experiments will provide new insights into the role of Cav-1 and FAS in PCa and will expand our understanding of the nature, the extent, and the biological significance of membrane lipid changes relevant to oncogenesis in PCa and possibly other malignancies.